Machhine Construction

1
Welcomes you to
Injection Moulding Technology - Part 3
2
Introduction

• Safety

• Telephones

• Registration

• Practical sessions

• Smoking

• Workshop access

• Refreshments

• Personal issues

• Messages

• Your contribution

3
Aim of course
To provide delegates with an in-depth knowledge
of the injection moulding process, in order to
competently and safely set up a range of moulding
machines, to achieve product quality and output.
4
Testing
Through out the course there will be Lesson
Assessments Class Exercises Evening
Assessments In your manual section 1, PAGE 8
5
Knowledge Assessment
Conducted at the end of the course,
successful completion of which

• Awards a P.T.I.C Level 3 Polymer
• Processing Certificate.

• Will assist personnel working towards the
• achievement of an Injection Moulding Diploma
• certificate.

• Allows progression onto practical element within
  
• Injection Moulding Technology - Part 3,
  resulting
• in the full award of a P.T.I.C Approved
  Technician.

6
Timetable
DAY 1 0900 ADMINISTRATION INTRODUCTIONS
0915 MACHINE CONSTRUCTION CLAMP END 1030
BREAK 1045 MACHINE CONSTRUCTION - INJECTION
END 1230 LUNCH 1300 SELF DEVELOPMENT
(review morning session) 1330 MACHINE CONTROL
INSTRUMENTATION 1500 BREAK 1515 MACHINE
CONTROL INSTRUMENTATION 1600 HEALTH
SAFETY 1645 FINISH (evening assessments and
Quality)
7
Timetable
DAY 2 0900 QUALITY(review evening
assessments) 1030 BREAK 1045 MACHINE PRACTICAL
No 1 1230 LUNCH 1300 SELF DEVELOPMENT (review
morning session) 1330 MACHINE PRACTICAL No
1 1515 BREAK 1530 MACHINE PRACTICAL No
1 1645 FINISH
8
Timetable
DAY 3 0900 REVIEW HOME WORK 0915 MOULD
TOOLS 1030 BREAK 1045 POLYMER
MATERIALS 1230 LUNCH 1300 SELF DEVELOPMENT
(review morning session) 1330 PROCESS
TROUBLESHOOTING 1515 BREAK 1530 PROCESS
TROUBLESHOOTING 1645 FINISH
9
Timetable
DAY 4 0900 HOME WORK REVIEW 0930 MACHINE
PRACTICAL No 2 1030 BREAK 1045 MACHINE
PRACTICAL No 2 1230 LUNCH 1300 SELF DEVELOPMENT
(revision of course) 1330 MACHINE PRACTICAL No
2 1430 BREAK 1445 DELEGATE FEEDBACK 1500 END
OF COURSE ASSESSMENT 1700 FINISH
10
Injection Moulding Technology
Part 3
Machine Construction
Clamping End
11
Session aim
To provide an in-depth understanding of the clamp
unit construction, operation and setting,
including variations in terminology.
12
Session objectives
By the end of the session you will be able to

• State the functions of the clamping unit.

• Name design alternatives for the clamp unit.

• Explain how to set and adjust the locking
  tonnage.

13
Terminology
Whenever possible Daylight 2-3 x depth of
moulding
14
Terminology
Mould Height
Moving Half
Fixed Half
15
Clamping end Component Parts
Moving Platen
Mould Clamping Cylinder
Ejection
Fixed Platen
Tie Bar
16
Direct hydraulic lock
Single Hydraulic Cylinder
17
Direct hydraulic lock
Advantages
1. Self lubricating 2. Low maintenance 3. Larger
tonnages 4. Tonnage set more accurately and
easier to adjust
Disadvantages
1. Slower movements 2. Larger pumps 3. Seals
expensive to replace 4. Increased power
requirements
18
Setting the mould height
19
Tailplate position adjusted
1.0mm
20
High pressure applied
1.0mm
21
Toggle locking mechanism
22
Hydraulic Driven Gear for Mould Height Adjustment
Toggle Lock Machine
23
Double Toggle Five point system
24
Toggle mechanism
Advantages
1. Fast movements 2. Natural acceleration and
deceleration 3. No forces on the clamping
cylinder when locked.
Disadvantages
1. High stress/strain 2. High maintenance 3.
Links need lubrication 4. Usually smaller than
2200 Tonnes
25
Ejection methods
26
Clamp tonnage estimation
Rule of thumb 2 - 4 tonnes/in2
480 KN
27
Clamp tonnage estimation
Rule of thumb 0.3 - 0.6 tonnes/cm2
168 KN
28
Clamp tonnage estimation
To be used as a guide line only!
CM
0.6 Tonnes per Sq CM
0.4/0.5
0.3
INCHES
3
2
29
Clamp end - 7 point plan

• Zero parameters
• Obtain movement
• Set positions
• Set speeds
• Set ejectors
• Set tonnage
• Check mould safety

30
Injection Moulding Technology
Part 3
Machine Construction
Injection End
31
Session aim
To provide an understanding of the construction,
operation, setting up and terminology, relevant
to the injection unit of the moulding machine.
32
Session objectives
At the end of this session you will be able to
33
Reciprocating screw injection unit
Feed Hopper
Fixed Platen
Reciprocating Screw
Injection Cylinder
Feed Throat
Nozzle
Drive Unit
Barrel Heaters
Carriage Cylinder
Check Valve
Barrel
Carriage
Complete the exercise in your course manual,
Injection Unit Components.
34
Screw rotation
What is back pressure?
What is decompression?
35
General purpose screw
Metering
Compression
Feed
36
Length to diameter ratio (LD ratio)
Hopper
Barrel
Diameter
60mm
Length 1200mm
Length 1200mm Diameter 60mm L/D ratio
1200/60 201
37
Compression ratio
Volume in this flight 1
Volume in this flight 3
Compression ratio 31
38
The check ring
39
Nozzle screw removal
Heater Band
End Cap
Nozzle
40
Nozzle types

• Open

• Shut-off

41
Spring loaded shut-off nozzles

• Shut-off

42
Hydraulic shut-off nozzles
43
Nozzle seating
Nozzle with too large a hole
Correctly sized nozzle
Nozzle with too sharp a radius
Nozzle with too shallow a radius
44
Hydraulic pressures
Maximum Pressure
Switchover Point
180 bar
What is specific pressure?
Actual Pressure
Injection Phase
Holding Phase
45
Specific Injection Pressure
Negri Bossi 100T
Shot Capacity
Specific Inj.Pressure
Screw Diameter
Hydraulic Pressure
Intensification Factor

72
1358
45
140
9.7
X
Screw area 15.9 sq. cm
Piston area 153.9 sq. cm
46
Hydraulic pressure - Specific injection pressure
Specific pressure (in front off the screw)
Typical 360 ton moulding machine
bar
psi
2100
2055
1800
25000
1510
1500
20000
70 dia (2.76 in.screw)
1200
1155
15000
60 dia (2.36in.screw)
80 dia (3.15 in.screw)
10000
600
5000
300
0
30
60
90
120
150 bar
Reading at pressure gauge
47
Mould cavity specific pressure
Flow path length 200 mm
Wall thickness 1.5 mm
500 bar Specific pressure
Material to be used is PVC
48
Projected area VS. clamp force
Mould projected area 600 Sq.cm
Specific pressure was 500 bar
300 tonne 3000 KN
Use the charts provided in your course manual to
complete the clamping force requirements.
49
Projected area
750 bar Specific pressure
50
Mould area VS. clamp force
90 tonne 900KN
51
Injection Moulding Technology
Part 3
Machine Construction
Injection End
52
Injection Moulding Technology
Part 3
Machine Control Instrumentation
53
Session aim
To provide an understanding of process parameters
and machine control devices to enable effective
setting of the injection moulding machine.
54
Session objectives
By the end of the session delegates will be able
to
55
Machine control parameters
56
Question 1A temperature closed loop control
system can be divided into three areas. What are
they?
Machine control instrumentation
57
Barrel temperature control
Heater
Closed Loop
Thermocouple
Controller
58
Factors affecting melt temperature

• Shear Back pressure
• Screw rotation speed
• Screw design

• Residence time

• Injection speed

• Ambient temperature

• Feed throat temperature

59
Question 2Name three types of heater bands?
Machine control instrumentation
60
Heater band types

• Mica

• Ceramic

• Ceramic (Knuckle)

• Aluminium

61
Question 3How can shear heat be generated
within the barrel?
Machine control instrumentation
62
Shear heat

• Frictional heat created by screw rotation

• Excess back pressure

63
Question 4Name three designs of thermocouples?
Machine control instrumentation
64
Thermocouples
Where a pocket cannot be created, a band type
thermocouple might be used, and where the
temperature of a fluid is to be measured, one
might resort to a leak proof compression fitting
thermocouple.
Bayonet Fitting
Armoured compensated leads
Compression Type
Ring Type
65
Question 5What is the function of a
thermocouple?
Machine control instrumentation
66
Thermocouples
Thermocouples are used to measure or sense
temperature.
Heater
Controller
T/C
67
Question 6How does a thermocouple work?
Machine control instrumentation
68
Thermocouples principle
Metal 1
Cold Junction
Hot Junction
Metal 2
The potential difference (volts) can be related
to the temperature difference.
69
Thermocouple output
TYPE J - IRON/CONSTANTEN
TYPE K - NICR /NIAL
TEMP DEG C 200 220 240 260
MILLIVOLTAGE 10.777 11.877 12.998 14.108
TEMP Deg C 200 220 240 260
MILLIVOLTAGE 8.137 8.938 9.754 10.560
70
Thermocouples
International colour codes for thermocouple
identification
IRON CONSTANTEN I/C Fe/con Fe/CuNi
71
Question 7Compare and contrast an ON/OFF
temperature controller to a PID controller. Which
one offers optimum control?
Machine control instrumentation
72
ON/OFF controller
Potentiometric
200oC
73
Temperature controllers
PID control is very accurate at recording
temperature
P.I.D (Proportional Integral Derivative)
74
Proportional
200oC
power
75
Proportional derivative
10 40 70 90
200oC
power
Slow approach More power for longer
76
Proportional integral derivative
10 40 70 90
200oC
power
100
Slow approach
77
Question 8Name three types of position
controllers? In addition, state which one of them
is the most accurate way at providing actual
feedback.
Machine control instrumentation
78
Positional control devices
Plunger
Roller
Limit switches
Limit switches are micro switches, which
automatically start and stop the movements of the
machine. They may be of the plunger, roller or
roller lever type.
Roller lever
On/Off control
79
Proximity switch
On/Off control
80
Linear Variable Differential Transducer
LVDT
Variable control
81
Rotary encoder
LVDT
Variable control
82
Question 9List three functions of a timer and
give examples.
Machine control instrumentation
83
Categories of time
Categories
Examples
Normal times Supervisory times Delay times
Holding time, cooling time, open cycle time
Mould safety time, injection time, cycle time
Delay screw back, Delay injection
84
Fundamental principles of speed pressure

• Pressure is created by resistance to a flow of
  oil.

• Pressure is controlled within the hydraulics
• of an injection moulding machine by the use
  of pressure relief valves.

• The flow of oil is varied in the hydraulic
  circuit by the use of speed or flow control
  valves.

85
Pressure relief valve
86
Flow / Speed control valve
87
Proportional Speed Control Valve
88
Proportional Pressure relief valve
89
Moog valveMicroprocessor electronics which
enables connection to a PC, for remote or on-site
diagnostic correction!
90
80 Bar
40 Bar
If injection pressure is reduced what will happen?
91
Essential principle
Remember!
Pressure affects flow (speed)
92
The accumulator
Nitrogen pressure
Nitrogen
Bag

• Dampen pulsation's and
• shocks within the system.
• Allow immediate operation
• of a service on demand.
• Stores oil under pressure.
• Provides high rate, hence
• high actuator speed.

Pressure build up
Oil flow
93
Mould fill and hold
(Example - 4 impression mould)
160 bar
Set values Injection pressure 160 bar
(max) Injection speed 50 Hold pressure 40
bar
90 bar
Injection Pressure
Holding Pressure
40 bar
Cushion
Fill Time 1.55 secs.
100mm
Injection stroke - mould 99 full
10mm
0
Hold position (switchover).
94
Injection end - 7 point plan

• Set shot weight hold pressure position
• Set screw speed
• Set injection speed
• Set injection pressure
• Set injection hold times
• Set cooling time
• Set injection initiation

95
Injection Moulding Technology
Part 3
Machine Control Instrumentation
96
Injection Moulding Technology
Part 3
Health Safety
97
Session aim
To provide an overview of the safety
requirements, relevant to the injection moulding
industry.
98
Session objectives
By the end of the session you will be able to

• Identify hazards associated with the injection
• moulding process.

• Name the safety systems required on a high
• risk guard.

• State a duty of the employee and employer
• under HASAWA 1974.

• List the necessary guard check requirements, as
• stated within the BPF Code of Practice.

99
Please Note!
The information presented during this training
programme is provided in good faith and for the
guidance of the delegates. Polymer Training
accept no responsibility for alterations to
legislation, which may have occurred without
prior knowledge of the Polymer Training
representative.
100
A Rochdale plastics manufacturer has been fined
140,000 after a Portuguese cleaner was crushed
to death by a pallet of bags weighing nearly one
and a half tonnes.
101

• Reporting of Injuries, Diseases and Dangerous
  Occurrences Regulations 1995 (RIDDOR) Change 6
  April 2012
• From 6 April 2012, subject to Parliamentary
  approval, RIDDORs over three day injury
  reporting requirement will change. From then the
  trigger point will increase from over three
  days to over seven days incapacitation (not
  counting the day on which the accident happened).
• Incapacitation means that the worker is absent or
  is unable to do work that they would reasonably
  be expected to do as part of their normal work.
• Employers and others with responsibilities under
  RIDDOR must still keep a record of all over three
  day injuries if the employer has to keep an
  accident book, then this record will be enough.
• The deadline by which the over seven day injury
  must be reported will increase to 15 days from
  the day of the accident.
• New guidance that explains the change will be
  available to download from the HSE website on 16
  January 2012.

102
Factories Act 1961 - Section 14

• Machines made before 1993 governed by Factories
  Act

• This Act was only applicable until 1997

• After 1997 the Factories Act, Section 14 ceased
  to be relevant to machine guarding

• The Factories Act was superseded by EC regulation
  Work Equipment Regulations in 1993

103
Health Safety - UK Legislation
104
Machine guards
Normal
Fixed
High
Fixed
Fixed
Fixed
Fixed
105
Other guards
106
Policing the law
The HSE have compiled their own guidance sheets,
that relate to various processes. These can be
obtained directly from the HSE and are deemed to
be the minimum requirements.
107
Powers of the Inspector

• They can enter at any time.

• They can ask for an individuals assistance.

• They can issue an improvement notice.

• They can issue a prohibition notice.

• They can prosecute anyone who has
• contravened a relevant statutory
• provision.

108
Corporate Social Responsibility
109
(No Transcript)
110
Injection Moulding Technology
Part 3
Health Safety
111
THE FACTORIES ACT 1961
SECTION 14
Every dangerous part of any machine shall be
securely fenced or safe by virtue of its position
.
Return
112
HEALTH AND SAFETY AT WORK ACT - 1974
Duties of Employers - Section 2
To ensure the health and safety of all employees
by providing

• Safe plant and systems of work.
• Safe handling, storage and transport.
• Information, instruction, training and
  supervision.
• Safe access and egress.
• A maintained and healthy working environment.

113
HEALTH SAFETY AT WORK ACT - 1974
Duties of Employees - Section 7
Return
114
B.P.F CODE OF PRACTICE
The B.P.F. Code of Practice is NOT a statutory
requirement, but it may be used in criminal
proceedings as evidence, together with other
regulations, stating that statutory guarding
requirements have been contravened.
This code may be used by H.M. Safety Inspectorate
as a basis for its enforcement procedures.
Return